SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d4738b8cfe623758ae96f82bcc85d4ede7f807402063c608a1261a4625afe65' 
  AND token = '/j7xOM6XlP/8rAYvzWIf0m7+ZNDZuqbtS/SCApHCK9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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