SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645d82120ccb4682e352173a9a0bdefbffc5457fe36d03d26d20bd0590456de3' 
  AND token = 'gBl+Fs9Wmw6jQIllAm71sqhZpvgq+4EQSO7kFPZaXJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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