SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a14d8c6195d2e6293643b8325425773b652951775feb2205b9b4aac8576a8197' 
  AND token = 'jj1rDqz+cxf0rwvRnnvZWlS2fIbWRHTtqaOLCQ/XkOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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