SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47d694e49ea5d581790f429d4fe81b1ed86d8f37a843ce5028c47632de69cbea' 
  AND token = '6PivsIa8yml81aXOoPVc5wBQPqndozdDKHN12ag5Nts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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