SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'cb1a8d26125ca417625b460a335c3f374201189fd0b336e28f55f64208338606' 
  AND token = 'QSbfsz2rAxtZgkE3fNilV2yLEXKa2i2kE9wFepQSjIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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