SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3298effb6d9fa4b34c78b48c01065eb25fbb8edef38cdb7da3339f6ac87694f2' 
  AND token = '/gfmCV+YXV5ZOxBhygXdXssJIsBnuUC1QzOyQhoshW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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