SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df79a5f4893d4eb940c9537c31c86f612f90bd32ab830f6248ee82ff403f6af1' 
  AND token = '//g1YhqJDrJdRl1P0GIDEc7QIcLzJ20GZI8xaUwkSC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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