SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50d556d148576f90995edf7973eeef07aca44f2c96f0fb15c53e126bb959d911' 
  AND token = 'YK52pDaKY5AOxLHOOWO5wYDNhUjJI3qX7fDtGuzJ4so=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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