SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c58598b03d805e04b14dc7289ba97de301d4c938fed88492ad690debc72affb3' 
  AND token = 'WLfemsUJnOm1u4Y9wyRosRsOEXCNBZSbH2WtIvSkBaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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