SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6e562c5191fd2b639fc8d5e930664c35453507a0476036f21b8d389d420c37d3' 
  AND token = 'H3/6T3kH3bORP7Oue8IRFW+IWpgHWo9ChpCWVOLyI0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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