SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5af516aa472e56175ea1de42b96fd23e9466941294254edc6340f9c340015655' 
  AND token = 'bgeDgJ1meRajHoMfJ3vMShf+A5bzMc2sICCiRgng3lM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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