SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a84cf64465ba89f5223ff05524df41ab77af1fe2d5e198b0f321b82e45de7818' 
  AND token = '3vVZGsM6GTzoqKrqmtLqwhh/alvABIU2Ljy1Gilq+5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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