SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '293c10b506ba418494972ac253c4f9fd16147f9434579ff63286f1919a2cd83a' 
  AND token = 'Fdy/ek94jefNkmKN9NzjX9HSTYahnbFGBuLALvIBdC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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