SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea7b75776955337b1113cfc18d64bbfd85f43b5027e9d244a8840c162754d129' 
  AND token = 'O4acJBriRRLzglPfZhAxHlxbb3u9gBmSDJPDfSTqUY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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