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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c90d8bf8011657ae297e40c083845d4fb46c177ba4965099e8b7a9565471bf83' 
  AND token = 'REr/KLm9ZUBJztN7Tn38O0bbMe+q0Her4c0uChlrXxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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