SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d55fff6f309173fe528369b7173f178daf174947c80d6e1b09512b105aed92b' 
  AND token = 'rvcOCqIEJGd3wQz2SrLJww29+5UeDNH0vo6ujLFX1b8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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