SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6626651e4776ef5dd678e3ced7614053b6338ceddeef1377e888f027bd60de9b' 
  AND token = 'm6C4meuBCylixysdfbD77RWDPriVW8C74UEOLzhapg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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