SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fef705d94d31674d8b403d25135f22d80b87dc09e143a24deb3092513d50ea9b' 
  AND token = '5vcX/LVmaOr7bgFZJCzoj6HADimuhNTizBF+A5oF4DM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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