SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f291f606f7e1b3fbb87188674fd3533d1af9027eb0a6ca2f2a601d38c20731' 
  AND token = 'weMLfjKYUjLgZIz1fXVFOnhxvDPhhz9/3S22KrtBcjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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