SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5256538cd35532487b0e10ddd9ac05c7f2d224c29e0824470e5b4a8ac51a02db' 
  AND token = 'Cks6fKSxTHShsTV0nyfcs+cQa1sPI9mvMbUm7HaLjWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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