SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fc1612293f56dc92ad882d6aff45cbef7f8e483217477565fad52b78129861a' 
  AND token = 'xCxJ4uDZkcvPIccB/uwAmMXTxegZgesa0yHpvn3vSQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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