SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c201669aa009576b65088d0d2b3f0740e581120839ce54d200913561d6a5cde2' 
  AND token = '6D/aMV9yzS4SXMWawVWzGoVC5U9XexqVbnrhViJ8qeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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