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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d6d6a651ba8f7dd51861ece7e452cae59d974e43f004dfa6b62b2099c2c6e4c' 
  AND token = 'uqn9Mxaaknf58IsiJynkYz/S7kTaJG6KhPuWboeBeCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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