SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6203c6bcd66f808496f2acbfc1f94bd7f011093048ea2e1c1c81505ed80a1ebb' 
  AND token = 'DSrA/dh0VHOg34sRdwdpa5vZivKlIEQ5CTV/zIjIeY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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