SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de36579bc387a319f27c0f57010e78d083f2d7d374aec09d5c1165b5a5de82f2' 
  AND token = 'htTHWq8MARvbevUFN3u3utPTAqE1UFaykHXoKRnosCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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