SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2278c343caa767b3c766103e9015b4fe782c7407ba62ae819ff52e34d93b6d1' 
  AND token = 'lnDJDKgosr0ebe1w5f9UFH7HxcTQD/njfzqTpPzQytQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}