SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f989f875cdc1816c8551c6afabcff6b46f797de4c7f342485fe3488788c375a5' 
  AND token = '57mKZ0QHafLPnnUU2nMagLFuN2cD8cVxXezgYSO6k3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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