SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b13521940894ad89879f0d61323e68f18d2f9cf94eeef664f3953383af27c329' 
  AND token = 'MIaYhKGdLzMmfnt+nJfZPBNMxa2ieSkdYxgm1awfK6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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