SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e84777f374e8345f7ef1273aeef843cbc05095dfd2cb258a28bbc6b423d8e4' 
  AND token = 'HGzARabVZk+JzfxJ12odKMPUIJChMP7aR/V0QdTwYv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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