SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '233eec2b81e410a595adde67cce29c29b105b784d1a90446a741078787f7ed82' 
  AND token = 'dQfxndwiE/jYMsHFZKQyVEYVg7XyIM1TfAOlLoWct8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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