SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d8841dfc8880febc62c9d338d9e567ad737a95a5726aba0ee43a6b65c3c470e' 
  AND token = 'dWzgKnvc0nvmM6srGKl0dEJeEQpwwYsRz3rBSeuKfdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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