SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74e2b1e6555ad70ceff379b423928a4e2b865674fff854494de9d5b8b87c4a0f' 
  AND token = 'kQb4LdMKcdXPjnRjFC2mCuslmilPQKHfmZOTHGKt3SM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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