SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '465de0c3e429d360d70517d2cbce17f3647998472403de22753d8aa184cff453' 
  AND token = '1/iY3RO6h97rEUmwpZ1XrVG4EZTu+sCI9TFS/vqe1fY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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