SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9821c2057f9a3a79edda733310a23e77ff459b374d9b54a9002f72299f74af5' 
  AND token = 'uIYkCEh0pl4CW4TqbgQcSEsyCnICGfofw7gX7tuKdek=' 
  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"
    }
  }
}