SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7cdf1518296dc0539333a28d7fabac6fa49c2646a23793320fcae97bb33890b' 
  AND token = 'vmlYWXoZdawY4eY11OBRWIOQvu502MIHccsfuOf2tYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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