SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8d91012d4200e3b31931429018c5b087fc63f68f168499267509970963d42d5' 
  AND token = 'yGeJF59Eqoa4z4DXJ3KvuNQh1vpRUZESnVytTPiO7Uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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