SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3656131f217dfad61bcccaf02347a8f107558afe7225f92cc559fea4a1eb2ed' 
  AND token = 'JLmq0U756+qxFnTYrcd11hx7qmfSEGMRxS8IQXiYebc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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