SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a9908168261f5712046af04d209013dd132e2261e7b037d3678d8089c1971e2' 
  AND token = '8fV5SIgCDKHC5KPbNxK1zOde83uSmVA2oRSuX+f3mHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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