SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15cc15d4b807f557d32fc7c1dba3d9a8f34470487fb6a2c605f0c63a63b0549e' 
  AND token = '9nT/jcsvdenb8SgyWFqYqHVDDQ/UjwhOqRcA/GLmDh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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