SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6f200632aea58df04b4e1c209f4d824a92a9a3a4142fea3dfb0ecba18fbe92a' 
  AND token = 'NWbbsd4wVSeTbDQEAe7fsXCUtBxy1ugVQoamlsTmjrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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