SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c089e4ba638c6aeac242ef64e5cad36fec528e926b6d225ce85769e1bb67161b' 
  AND token = 'elLlKg7KL+WIZUz4Aeae1AELYUS0ExoPWEZdPqc3VrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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