SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2c670110264bf0018c96874f165d82e584c290733849974ee0db6223957c646' 
  AND token = '/pgYYhE9MNYOFxim99RG3XPfBMDhgEKp8nhTH+PLPSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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