SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '699a1cdd796b9b317daf871f363389400071fac5bdcf4490cbc70637caff3e93' 
  AND token = '16iHYkremt0EPEjQjrq0V+GmkdGEMaGvnkRp2LsUg64=' 
  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"
    }
  }
}