SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdcf5b1c131d816710df6ce86641859ec995b59f8e270bafc78eb4fab29d3ebf' 
  AND token = '/B7+zQfJhOmtzTQ2Vr4B1EXaL2m5sx2TAnw9Jgq7L5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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