SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cb8f005991b11cb8b0650e8bce399abf2c86535ac6359ea5ab21f848b5a000d' 
  AND token = 'kdeSoJLmZ9bAv1euqzFBBr5EQyBKfVlQ+FfkYO5iMro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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