SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4db121a5ce6396301de599fc4dbf9dd4fc4a5fba175003d43ce25049fbf301d4' 
  AND token = 'Fls23hYTrTUQfcs+NG05fTOJZiXr5T/DF+TvcEAEjIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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