SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b74d44907d511a1588a792ad412a814635a4e263ed361f5970d62d5be7e6a680' 
  AND token = 'SzlwEUdZVhyfpDUC1OV/A7R+iYNgwXoVpVAudMXyVP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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