SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5225e69e42ba888019fc5ddc0827ace35867978de7fa838327ea22c781712ace' 
  AND token = '78PUDevl6nXy67oViPbFFLclpcjlBRH+M7zVjRHsoxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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