SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7f51946863d5d04b4297d4781b5348757def77193e346da0292a96f31d17a8e1' 
  AND token = '10FHRTW+8OBqnrB7RtsFv7RW28HG/yiVyHrsGtW1CUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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