SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a62a08da7e171eaf3829149450f48fa968c2747b4809ab1a541a0660d536d31' 
  AND token = '94UBOOlMKF5kv+iAPxWpGUeV07lU1numxHjJRZfrKIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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