SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4ebf849d1b5671011626896ff05cb21cf3c9e74aaf1cda6893dc70cd9f53649' 
  AND token = 'LQuYyETcVTdYhkAMPa/YfYA4WXw1ULgptbSCF1pS0ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}