SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6259cf176ab534dc45c0fd78396323071107a738579f264d3f9d3e1eb360b15' 
  AND token = 'S6Fx3WTRomhRj+mM/NMfVlvpbzKgxz91kTQu1VYIUcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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