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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b29813f34802d143645f9f8ba32ca9cdc1b4e62e23cb4ee9ee3bb27f1d723c9a' 
  AND token = 'TVZFG0DAeiRdCRV88Pzb3SwVFYXixIOXgbkes8tR4P0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}