SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eef98a64a6103eeb204ff921680d466ed28004fd4f8686c3954934d250a990f' 
  AND token = 'cL92zVKadpkylcJyOreuMMD6ypaUJuXesAT300Ky4UE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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