SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f190510eaa8855348a979cc12e2d6d083cdca653e058226b9bedbfafbcad7178' 
  AND token = 'tbdc+Qq9m5ruDJTBTWWlWOR+Pjf6Heovkbz37aMgRj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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