SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '60c8278785182981e484919501a755b2cab6fcfafb52c4e52e567d92084a513c' 
  AND token = '8LAlXohDmNqxgPSm+2V6BFOwM6dXC0z1xNwGPjIiQpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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