SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27da1ae5bade4a1d3c78073577ff72bb2c3fc8a6f6e48bd179d84f46eb5e817d' 
  AND token = 'k+Gkat0HkxbzrjKvEI/Zh8dLoteMgzyams49/rjWWLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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