SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f9127a11271292e51e401ee8686e59b8afac115475a2116f1b981d272de8caa' 
  AND token = 'NaT7cySvd3yViGMSY9BAWjerO6BxjmXikm+yLQpBUbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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