SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fda8a89ea3c707450951179416b291554f8975392e9d861ebd66007784d37b3' 
  AND token = 'kU8OjxSJb7z9+aLdvzJRPFl8AllrWhMyuBA3d8tevps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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