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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c409def9c5c213e2fcad49c04af6d135c3f4956097cafb7d5bf8feda50b70bd9' 
  AND token = '4PfoEBOPaIqlllNbgGgGMzPJMtPpzsv2In250o4rhxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}