SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51a8bcd8b984272a8dba6f642280a77cebc80199defce70e3d449852b1229286' 
  AND token = 'E2mMrjYEjE+x3/p6a1LnUOuKNsoA939yfxEtET/TmqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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