SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29e4258af3d0d164f6bc3413ed1fd9870c1e16eb256a0379c04776d356e3bc54' 
  AND token = 'SckYQOYrrceDJksHsJgx2OEuezeCzcSbonvFUNBx4yM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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