SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40243905d013df19172da1ccce82b8a221b69138b9a79ecf0c6ea22dcba4012d' 
  AND token = 'AvqW1UUnnv5LnzAElFmB1dI659S2jTCPAgYkMJR9xkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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