SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a56f1605a2fa0c472718aaa369781f983f3693c93932f1dadb4d8d24fde6caf' 
  AND token = '8FxbxiV6LclPfCBitUzpKv90PBrcYNJDuviR1/TFhFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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