SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '348825bb3fb82436856adced290873c473dd5988bfdf697bfc89256ad3baa4f4' 
  AND token = 'go1hM4a3jFZ/RaZ28/E8V5ZVULWrKJXnjpT+4wplFG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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