SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f05eaa079103b3db2fd3f2ef20a6d78613f965e2293b6c6af3fa28d8155948' 
  AND token = 'UxDAGKiPhFzIErN45XlRNAqdG/AAoPF8o8GSvImyjJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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