SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7771d4c1381311becfcf2154b2c9220992fed48e765690379993373b09e9992c' 
  AND token = 'gVPKtaNnfUlhOOsl7L0kEMOjjMiIlocshqGATgITRy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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