SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e6aaafdcfb0997a12b99666317d6e5043686214fd57c0b21b89a50bfc53e57b' 
  AND token = 'b+jX6CrVkh2BZmUHIoZFGaLU8PXQaC7vslVHML8QQck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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