SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291f36da890dd7b1c492db413f5b4357c56bdb0240d93d5ee0d1865f5ca14bfe' 
  AND token = 'La/MBeZDRIsdO7/hM9qJ/DvgmRZcfXqrbcpU+nXYJQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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